Continuous heat treat furnace with a conveyor



CONTINUOUS HEAT TREAT FURNACE WITH A CONVEYOR Filed Sept. 16, 1966 R. F. REA

Jul 18, 1967 2 Sheets-Sheet 1 INVENTOR: RUBERT f. REA

v L x 4 x 1 ATTb's.

R. F. REA 3,331,593

CONTINUOUS HEAT TREAT FURNACE WITH A CONVEYOR July 18, 1967 Shets-Sheet Filed Sept. 16, 1966 INVENTOR: .RUBEHT FEM.

ATTYQ.

United States Patent ce 3,331,593 CONTINUOUS HEAT TREAT FURNACE WITH A CONVEYOR Robert F. Rea, Bloomfield Hills, Mich., assiguor to Champron Spark Plug Company, Toledo, Ohio, a corporation of Delaware Filed Sept. 16, 1966, Ser. No. 530,054 4 Claims. (Cl. 2638) ABSTRACT OF THE DISCLOSURE A furnace through which materials are transported by means of a continuous conveyor. The furnace is constr-ucted so that the conveyor can be operated at relatively cold temperatures, or can be stopped indefinitely while the furnace is held at an elevated temperature without damage thereto. In essence the furnace comprises a 1ongitudinal support structure, a pair of rails on the support structure, a longitudinal chain conveyor having rollers that roll along the rails, a longitudinal heating chamber positioned above the chain conveyor, and work carriers fastened to links of the conveyor. The construction is such that the work carriers substantially fill an opening in the floor of the heating chamber, and are fitted in such close end-to-end engagement to substantially close oil? the floor of the heating chamber.

This is a continuation-in-part of copending U.S. application Ser. No. 380,461, filed July 6,1964, now abandoned.

The invention relates to a furnace through which articles are moved by a continuous conveyor, and more particularly to a furnace of the above-described type in which the conveyor can be held stationary over prolonged periods while the heated chamber is held at an elevated temperature.

An object of the present invention is the provision of a new and improved furnace through which materials are transported by means of a continuous conveyor, and which furnace is so constructed that the conveyor'mechanism can be operated at relatively cold temperatures and thus be lubricated by conventional hydrocarbon lubricants.

Another object of the invention is the provision of a new and improved furnace of the above-described type in which the conveyor can be stopped indefinitely while the furnace is held at an elevated temperature without damaging the conveyor structure.

A still further object of the present invention is the provision of a new and improved furnace of the above described type having a conveyor beneath the furnace with work carriers projecting up through an opening in the floor of the furnace and which is so constructed that bricks or other similar insulating materials can be placed upon the conveyor and transported into a position wherein the bricks overlap floor areas of the furnace on opposite sides of the conveyor to substantially seal off the opening through which the work carriers project and insulate the conveyor structure from the furnace chamber.

The invention resides in certain constructions, combinations and arrangements of parts; and further objects and advantages of the present invention will become apparent to those skilled in the art to which it relates from the following description of a preferred embodiment described with reference to the accompanying drawings forming a part of this specification, and in which:

FIG. 1 is a plan view of a heat treating structure comprising a furnace and a continuous conveyor which extends beyond opposite ends of the furnace and which embodies principles of the present invention;

FIG. 2 is a longitudinal vertical sectional view taken approximately along the longitudinal line 22 of FIG. 1 and along the vertical line 22 of FIG. 3;

FIG. 3 is a fragmentary sectional view taken approxi-' mately on the line 3-3 of FIG. 2;

FIG. 4 is an isometric view of a ceramic support block which is carried by a metallic conveyor mechanism located beneath the floor of the furnace, and which projects up through an opening in the floor of the furnace to sup port articles to be fired in the furnace; and

FIG. 5 is a fragmentary sectional view showing the top portion of the conveyor structure and the floor of the furnace and indicating the manner in which brick can be supported by the conveyor structure to seal ofi the open ing in the floor of the furnace.

The furnace 10 shown in the drawing is supported from a steel structure that comprises spaced-apart cross channels 11 on top of which are four longitudinally extending channels 12, best seen in FIG. 3 in which only two of the channels 12 are shown. A pair of base plates 13 are welded to the top of the channels 12 to form a bottom support for the brickwork of the furnace, and the base plates 13 have upwardly extending portions 14 that are generally in line with the upper webs of the center channels 12. The upper sections of the base plates 13 are laterally turned as at 15 to support the center portion of the brick floor of the furnace. The adjacent edges of the laterally turned portions 15 of the plates 13 are spaced apart and stop short of the edges of a longitudinally extending opening 16 in the brickwork 17 which forms the center portion of the floor of the furnace 10.

Although the internal heating chamber 18 can be of any suitable shape providing that it has generally flat floor areas on opposite sides of the opening 16, the heating chamber 18 shown is generally rectangular in cross section, having a height which is somewhat greater than the width. The top and side walls of the furnace are formed from several layers of brick, as is the floor area outwardly of the upwardly extending portions 14 of the base plates 13. The side walls and ends are covered with steel plates 20, held together at the top by cross members 21 to provide a rigid support for the brickwork. The opposite ends of the furnace are generally closed except for an inlet opening 22 and an outlet opening 23 of a size large enough to pass various materials as will later be described. The heating chamber 18 may be heated in any suitable manner, such as by gas burners, but in the embodiment shown in the drawing, the chamber 18 is heated by rod-shaped electrical resistors 24 to which electricity is conducted and the resistance of which causes heat to be generated in the heating chamber 18.

The conveyor structure 25, for moving articles to be fired through the furnace 10, generally comprises a pair of rails 26 bolted to opposite upturned legs of a channel 27. The bottom of the channel 27 is supported by means of L-shaped brackets 28 having a vertical leg bolted to 'the cross channels 11 and a horizontal leg bolted to the web of the channel 27. The conveyor structure 25 further includes an endless chain of conventional construction comprising parallel, spaced-apart rollers 29, adjacent ones of which are abutted on opposite sides by inner links 30. Short connecting pins, not shown, pass through the rollers 29 and inner links 30 to secure a pair of adjacent rollers 29 together, and the rollers on opposite sides of a pair connected by the inner links 30 are connected by outer links 31. At predetermined intervals, the short connecting pins, not shown, are replaced by long pins 32 which extend out over the top of the rails 26, and on opposite ends of which identical conveyor rollers 33 are positioned for riding on top of the rails 26. Generally U-shaped workcarrier supports 34 made of cast iron are positioned above the endless chain, and the supports 34 are carried on the pins 32 by means of a pair of depending blocks 35 which rollers 33 'to prevent endwise movement of the conveyor rollers 33 off of the pins 32. Lateral shifting of the conveyor structure relative to the rails 26 is prevented by the bottom of the depending blocks 35 which are located inwardly of the upwardly extending legs of the channel 27 with but a small running clearance therebetween.

The endless chain of the conveyor structure is moved with a uniform continuous motion by means of a head sprocket 39, shown'in FIG. 1, located sufficiently forward of the discharge end of the furnace to provide for adequate cooling. The head sprocket 39 is driven by a suitable electric motor 40. The endless chain passes over the head sprocket 39 and then returns beneath the longitudinal channels 11 where the conveyor rollers 33 roll on top of other conveyor rails, not shown, on their way back to a tail sprocket 41 located a sufficient distance rearwardly of the furnace to provide space for conveyor loading machines 42. The conveyor loading machines 42 are -d-riv en synchronously with the conveyor drive motor 40 so as to place objects to be heated on the conveyor structure as will later be described.

Although the furnace can be used in substantially any heating application, it is shown in the drawing as being used to anneal metal sleeves. The sleeves to be annealed are placed in an opening 43 in ceramic work carriers 44. FIG. 4 of the drawing is an isometric view of a ceramic work carrier 44. The work carriers 44 are placed in the U-shaped supports 34 and locked in place by a pair of setscrews 45 threaded through the upstanding legs of the supports 34 and turned against the bottom sides of the carriers 44.

The ceramic work carriers 44 have an upper portion 46 which is made from a refractory material which will withstand alternate heating and cooling, and a lower portion 47 which fits within the support 34 and has good heat insulating properties. The portions 46 and 47 of the carriers 44 can be fused together or can be fired separately and then bonded together by means of a suitable vitreous material. The carriers 44 have a width which substantially closes off the opening 16 in the floor of the furnace, from side to side allowing only sufficient clearance 48 between each side of the carrier 44 and the side wall of the opening 16 to accommodate dimensional changes and lateral shifting of the conveyor structure relative to the opening 16. .While the carriers 44 can project up into the furnace chamber 18 any desired distance, the top edge of the carriers 44 of the preferred embodiment will extend above the brickwork 17 forming the floor of the furnace only a short distance, for example inch, for reasons which will later be explained. The motor 40' runs continuously to advance the bodies through the furnace 10 and along the cooling discharge end of the conveyor where they are unloaded continuously. Thereafter the carriers 44 pass over the head sprocket 39 and hang downwardly to allow any foreign materials to fall out of the carriers 44 as they return to the loading endof the conveyor. It will be seen that this continuous operation alternately heats the carriers 44 while they pass through the furnace 10, and thereafter alows them to cool off to a temperature approaching ambient conditions before again entering the furnace 10. During the time that the conveyor 25 is running continuously, the cooling cycle for the carriers 44 helps to limit the amount of heat that is transferred from the furnace 10 to the conveyor 25 which can be lubricated by means of conventional hydrocarboncontaining greases.

' It will be seen that the conveyor 25 is located very close to the heated chamber 18 of the furnace 10 so that considerable heat is transferred from the heated 4 chamber 18 to the region of the conveyor 25. While it may not be necessary in all instances, the preferred embodiment of the furnace 10 is provided with longitudinally extending conduits 49, shown in FIG. 3 positioned between the bottom of the brick 17 forming the floor of the furnace 10 and the top of the conveyor 25. Water is continually circulated through the conduits 49 to remove some heat from the bottom surfaces of the furnace 10 and also to remove heat from the setter supports 34 by radiation and hence keep the conveyor 25 cool. The conduits 49 may be of any suitable construction and are shown having a generally rectangular cross section with one fiat side positioned against the lateral turned portion 15 of the base plates 13 and held in place by suitable brackets 50. While it may not be necessary in all instances, the structure shown in the drawing is also provided with a longitudinally extending conduit 51 positioned on top of the web of the support channels 27 beneath the roller chain to remove the heat from the conveyor rails and chain. The conduit 51 may be of any suitable cross section and is shown as being similar in construction to the conduits 49. A liquid coolant such as water is introduced into one end of the conduits 49 from supply conduits 52, and is removed from the other end of the conduits 49 by drain conduits 53. The conduit .51 is supplied with a coolant by means of a supply conduit 54,

and the coolant is removed therefrom by an exhaust ing the conveyor structure to reach damaging tempera-.

tures. For example,,it is desired to provide an arrangement wherein the furnace and conveyor can be operated for one or two shifts, and thereafter the conveyor structure can be stopped overnight while the furnace is maintained at approximately its normal elevated temperature 1 so that damage to the brickwork will not take place, and 'so that the furnace will be ready to be used almost immediately upon resuming operations. In order to limit the amount of heat which passes through the bottom of the furnace 10 to the region of the conveyor 25 during prolonged periods of shutdown, the furnace 10 and the car- 7 riers 44 are constructed so that the top of the carrier 44 projects just slightly above the bottom flat surface of the brick 17 of the floor of the furnace. A plurality of flat bricks 55, shown by broken lines in FIGS. 2 and 3 and in solid lines in 'FIG. 5, are placed upon the conveyor 25 in end-to-end relationship while the conveyor 25 is running so that the bricks 55 are transported in an end-toend relationship throughout the entire length of the furnace. Each brick '55 has an opening 56in its bottom surface position which overlies the opening 43 of the carriers 44, and a suitable ceramic body 57 projects upwardly out of the opening 43 into the opening 56 to prevent shifting of each of the bricks 55 on its carrier 44. Because the tops of the carriers 44 project just slightly above thebottom surface of the brick 17 of the furnace chamber 18, the bottoms of the bricks 55 are out of sliding engagement with the surface of the brick 17 and overlap an appreciable portion of the bottom surface of the brick 17 on opposite sides of the opening 16 in the floor of the furnace. The bricks 55 prevent direct radiation through the clearances 48, and also greatly restrict heat transfer by conduction through the carriers 44. After the bricks .55 have been fed through the furnace until they extend through the openings 22 and 23, additional bricks 55' can be placed in the openings 22 and 23, if-desired, to substantially seal off the inlet and outlet openings 22 and 23. Very little heat is, therefore, required to keep the furnace chamber 18 at the desired elevated operating temperature during the time that the bricks 55 are in place and the conveyor 25 remains stationary.

While the invention has been described in considerable detail, it is not desired to be limited to the particular embodiments shown and described; and it is intended to cover hereby all novel adaptations, modifications and arrangements thereof which come within the practice of those skilled in the art to which the invention relates.

What I claim is:

1. A continuous heat treat furnace comprising: a longitudinally extending support structure, a pair of longitudinally extending spaced-apart rails on said support, a longitudinally extending chain conveyor having supporting rollers that roll along said rails, a longitudinally extending heating chamber positioned a predetermined distance above said chain conveyor, said chamber having a floor with a longitudinally extending floor opening of uniform predetermined width positioned over said conveyor, and a plurality of Work carriers individually fastened to spaced-apart links of said conveyor, said work carriers having upright portions of a width which substantially fills said opening in said floor, being fitted in close end-to-end engagement to substantially close ofi the floor of said heating chamber, and having a lower thermal insulating layer adjacent said conveyor and an upper thermal shock resistant layer which is exposed to said heating chamber.

2. A continuous heat treat furnace comprising; a longitudinally extending support structure, a pair of longitudinally extending spaced-apart rails on said support, a longitudinally extending chain conveyor having supporting rollers that roll along said rails, a longitudinally extending beating chamber positioned a predetermined distance above said chain conveyor, said chamber having a floor with a longitudinally extending floor opening of uniform predetermined width positioned over said conveyor, a plurality of work carriers individually fastened to spacedapart links of said conveyor, said work carriers having upright portions of a width which substantially fills said opening in said floor, and said upright portions being fitted in close end-to-end engagement to substantially close off the floor of said heating chamber, and a pair of cooling fluid conduits positioned between said chain conveyor and said floor of said heating chamber and on either side of said longitudinal floor opening whereby the temperature of said chain conveyor is prevented from exceeding a safe limit during continuous operation of said m c 3. A continuous heat treat furnace comprising: a longitudinally extending support structure, a pair of longitudinally extending spaced-apart rails on said support, a longitudinally extending chain conveyor having supporting rollers that roll along said rails, a longitudinally extending heating chamber positioned a predetermined distance above said chain conveyor, said chamber having a floor with a longitudinally extending floor opening of uniform predetermined width positioned over said conveyor, a plurality of work carriers individually fastened to spaced-apart links of said conveyor, said work carriers having upright portions of a width which substantially fills said opening in said floor, and said upright portions being fitted in close end-to-end engagement to substantially close off the floor of said heating chamber, said heating chamber having inside floor surfaces on opposite sides of said opening which are of constant cross section and elevation above said rails for the length of said floor opening whereby a plurality of bricks laid end-to-end on said work carriers can be advanced into said furnace to overlie said floor opening and substantially seal off and isolate said conveyor from said heating chamber.

4. A continuous heat treat furnace comprising: a longitudinally extending chain conveyor, a longitudinally extending heating chamber positioned a predetermined distance above said chain conveyor, said chamber having a floor with a longitudinally extending floor opening positioned over said conveyor, a plurality of work carriers individually fastened to spaced-apart links of said conveyor, said work carriers having upright portions of a Width which substantially fills said opening in said floor from side to side, and said upright portions being fitted in close end-to-end engagement to substantially close 01f the longitudinal extent of said opening in said floor of said heating chamber, and a pair of cooling fluid conduits positioned between said chain conveyor and said floor of said heating chamber and on either side of said longitudinal floor opening whereby the temperature of said chain conveyor is prevented from exceeding a safe limit during continuous operation of said furnace.

No references cited.

FREDERICK L. MATTESON, IR., Primary Examiner. I. I. CAMBY, Assistant Examiner, 

1. A CONTINUOUS HEAT TREAT FURNACE COMPRISING: A LONGITUDINALLY EXTENDING SUPPORT STRUCTURE, A PAIR OF LONGITUDINALLY EXTENDING SPACED-APART RAILS ON SAID SUPPORT, A LONGITUDINALLY EXTENDING CHAIN CONVEYOR HAVING SUPPORTING ROLLERS THAT ROLL ALONG SAID RAILS, A LONGITUDINALLY EXTENDING HEATING CHAMBER POSITIONED A PREDETERMINED DISTANCE ABOVE SAID CHAIN CONVEYOR, SAID CHAMBER HAVING A FLOOR WITH A LONGITUDINALLY EXTENDING FLOOR OPENING OF UNIFORM PREDETERMINED WIDTH POSITIONED OVER SAID CONVEYOR, AND A PLURALITY OF WORK CARRIERS INDIVIDUALLY FASTENED TO SPACED-APART LINKS OF SAID CONVEYOR, SAID WORK CARRIERS HAVING UPRIGHT PORTIONS OF A WIDTH WHICH SUBSTANTIALLY FILLS SAID OPENING IN SAID FLOOR, BEING FITTED IN CLOSE END-TO-END ENGAGEMENT TO SUBSTANTIALLY CLOSE OFF THE FLOOR OF SAID HEATING CHAMBER, AND HAVING A LOWER THERMAL INSULATING LAYER ADJACENT SAID CONVEYOR AND AN UPPER THERMAL SHOCK RESISTANT LAYER WHICH IS EXPOSED TO SAID HEATING CHAMBER. 